I'm actually thinking about changing my play schedule. Compared to about 6 months ago, the regular cash tables on Full Tilt seem to die a few hours earlier than before.  At least that is my perception - I wish I had some data to back it up.  Part of this is just mid to high stakes full ring dying out on FT, but I think part of it may be structural. By "structural," I mean one of more of: (i) Rush cannibalizing the player pool, (ii) mass multitablers moving over to Stars because the tables die out earlier (vicious cycle), (iii) less US players (especially from the West coast), etc. I'm hoping the latter is because of something like WSOP being around the corner (and people are trying to earn their seats) or people in school taking exams, rather than UIGEA making it difficult for people to deposit online.

I will from time to to look at the market trend for online poker.  Whenever you are involved in any business, you need to keep on top of what is going on in your industry.  I don't think the graph of FT's 6 month trend in number of cash game players captures Rush poker, which comprise a decent number of players.  But I could be wrong on this.  [EDIT: PokerScout confirmed that their data INCLUDES Rush data]  But since Rush was introduced in February, the right half of the graph is troubling.  And it somewhat backs up what I've been noticing about the tables dying out earlier over the past few months.  But it's hard to make any strong judgments on so little data, especially when seasonality could be involved.  I remember last fall there was a huge surge, so you need to take the data with a grain of salt.  But I would get alarmed if the average number of cash game players ever got below 10K tho.

FWIW, the 6 month trend for PokerStars (the largest site) increased marginally over the past 6 months, which is a good sign.  The trend over the last 6 months seems to be that Stars did better and everyone else did worse.  You need a certain critical mass to be viable as a poker site (so you have enough tables for multitablers, enough selection of games, bigger tournaments, etc).  Unfortunately for all other sites other than the top two, none of them have critical mass and barring an aggressive move, they will probably continue to slide. 

It seems like the peak number of tables online occurs around 2PM.  To be honest, I was shocked that the peak number of tables occurred in the early afternoon.  I thought it was in the late evening for sure.  I don't have the data from a year ago, but I could swear the drop-off in the evenings wasn't as large as it is now.  I'm wondering if there's been a drop-off in US participation.

[EDIT:  I just found out the times on that web site were in PST.  We ESTers always assume all times are in EST.  So 5PM EST seems like a more reasonable estimate for the peak traffic.]  So rather than playing from 8PM to 4+AM EST, as I had been before my recent playing binge, I think I can play from 11AM to 4PM, spend a few hours with the family and then maybe a few hours after 8PM.  This way I can be on a somewhat normal sleep pattern.  Still need to think about this some more tho.